'The paper begins by examining the functions of input-oriented and output-oriented legitimating arguments in liberal democracies. At the European level, input-oriented arguments remain weak, but legitimacy problems are generally avoided since the policies which can in fact be adopted under prevailing institutional conditions are still based on broad intergovernmental consensus. For a variety of new policy challenges, however, consensus on the choice of European solutions is unlikely to be reached, even though member states are unable to cope with such challenges on their own. The resulting problem-solving gaps, which may undermine political legitimacy nationally and in the EU, could not be legitimately overcome by moving from consensual to majoritarian governing modes at the European level. What could help are modes of differentiated integration which allow groups of member states to adopt consensual European solutions applying only to members of the group.' (author's abstract)|